Internal Medicine
UACR Test (Urine Albumin-to-Creatinine Ratio): Normal Range, Results, and What High Means
Reviewed by the JordanMedHub Medical Editorial Team · 9/12/2026
Quick Answer
UACR is a urine test that detects early kidney damage, often before other kidney tests show a problem — the normal range, A1–A3 categories, and why one high result isn't a diagnosis.
In this article
The urine albumin-to-creatinine ratio (UACR) is a simple urine test that measures whether the kidneys are leaking small amounts of a protein called albumin into the urine — often one of the earliest detectable signs that the kidneys' filtering units are under stress, well before other kidney tests change.
Quick Answer
UACR compares the albumin and creatinine in a single urine sample. A normal result is generally below 30 mg/g. Higher results — 30 to 299 mg/g, or 300 mg/g and above — suggest increasing amounts of albumin leakage, which can be an early sign of kidney damage, especially in people with diabetes or high blood pressure. One elevated result is usually confirmed with repeat testing before it is treated as a real finding, and it does not by itself mean permanent kidney damage.
What Is a UACR Test?
UACR stands for urine albumin-to-creatinine ratio. It is also called a microalbumin test or an albumin-creatinine ratio (ACR) test. It uses a single urine sample to estimate how much albumin the kidneys are letting through — information that used to require a full 24-hour urine collection.
What Does UACR Measure?
The test measures two things in the same sample: albumin, a protein that healthy kidneys normally keep in the blood, and creatinine, a waste product the body makes at a fairly steady rate. Comparing the two corrects for how concentrated or dilute the sample is, so a single random sample can stand in for a 24-hour collection. The National Kidney Foundation describes UACR as a way to estimate how much albumin would pass into the urine over 24 hours from one spot sample.
Why Doctors Order a UACR Test
Healthy kidneys keep most albumin in the blood. When the kidneys' filtering units (the glomeruli) are damaged, even mildly, small amounts of albumin start to leak through — often before blood-based tests like creatinine or eGFR show any change. This makes UACR a useful early-warning test, particularly for people whose kidneys are at higher risk because of diabetes or high blood pressure.
Who Should Have UACR Testing?
UACR testing is especially recommended for people with diabetes or high blood pressure, both leading causes of kidney damage that can develop silently. The NIDDK advises that people with diabetes be checked every year; people with high blood pressure, heart disease, or a family history of kidney disease should ask their doctor how often they need it. Our guides to diabetes, high blood pressure, and kidney function tests cover the broader picture of kidney monitoring for these conditions.
How the UACR Test Is Done
UACR needs only a single "spot" urine sample, collected at a lab or clinic — not a 24-hour collection. Tell the lab or your doctor if you have had a fever, a urinary tract infection, intense exercise in the past day, or (for women) are menstruating or have urinary bleeding, since the National Kidney Foundation notes these can all cause a falsely elevated reading.
Does UACR Require Fasting?
No. UACR does not require fasting, and there is no special diet preparation. The main things to avoid beforehand are intense exercise in the 24 hours before the test, and testing during a fever, infection, or menstruation if that can be scheduled around.
UACR Normal Range
A normal UACR is below 30 mg/g, according to the NIDDK and the National Kidney Foundation. Results are not tied to a person's age — there is no separate "normal range" for children, older adults, or any other age group published by these sources, so the same threshold is used to interpret results.
UACR Categories
Kidney organizations divide UACR into three categories, often labeled A1 to A3:
| Category | UACR (mg/g) | UACR (mg/mmol) | What it usually means |
|---|---|---|---|
| A1 — normal to mildly increased | Below 30 | Below 3 | No evidence of meaningful albumin leakage |
| A2 — moderately increased | 30–299 | 3–30 | Sometimes called "microalbuminuria"; early kidney damage is possible |
| A3 — severely increased | 300 or above | Above 30 | Sometimes called "macroalbuminuria"; more significant albumin leakage |
Labs in some countries, including the UK, report UACR in mg/mmol rather than mg/g; the National Institute for Health and Care Excellence (NICE) treats a confirmed ACR of 3 mg/mmol or more as clinically important. The two unit systems describe the same underlying categories, just on a different numeric scale.
What a High UACR Means
A UACR above 30 mg/g can suggest kidney disease even when eGFR, the blood-based estimate of how well the kidneys filter, is still in a normal range. That is why UACR and eGFR are used together rather than either alone. A single high result is a signal to look further, not a diagnosis by itself — more albumin in the urine usually means the kidney's filtering barrier is under more stress, even if other tests have not changed yet.
Temporary Reasons UACR Can Be Elevated
A UACR reading can be temporarily raised by things that have nothing to do with ongoing kidney damage, including a fever or active infection, a urinary tract infection, intense exercise shortly before the test, menstrual or other urinary bleeding, and poorly controlled blood sugar or a recent blood pressure spike. Because of this, the National Kidney Foundation and NIDDK both note that decisions are rarely made from a single sample — an elevated result is usually repeated once or twice before being acted on.
Persistent Albuminuria and Kidney Disease
Albuminuria becomes clinically significant when it is persistent, not just present on one occasion. Kidney disease guidelines generally require an abnormal finding to be confirmed on repeat testing, and chronic kidney disease itself is defined by abnormalities of kidney structure or function that are present for three months or more. A single elevated UACR is a reason to retest and look at the bigger picture — it is not, by itself, the same as a diagnosis of chronic kidney disease.
UACR and Diabetes, High Blood Pressure, and Chronic Kidney Disease
Diabetes and high blood pressure are the two leading causes of chronic kidney disease, and both can damage the kidneys' filtering units gradually and silently, often without early symptoms. Regular UACR testing is how this kind of damage is usually caught early, while it may still be possible to slow it down with better blood-sugar control, blood-pressure control, and sometimes specific medicines. A rising UACR in someone with diabetes or high blood pressure is a reason to review how well those conditions are controlled, not only a kidney-specific concern on its own. See our guides to type 2 diabetes, hypertension, and chronic kidney disease for more on each condition.
UACR vs Creatinine vs eGFR vs Urinalysis
These tests answer different questions and are often used together:
- UACR looks for albumin leaking into the urine — a sign of damage to the kidneys' filtering units.
- Serum creatinine and eGFR (kidney function tests) estimate how well the kidneys are filtering blood overall. A person can have a normal eGFR and an abnormal UACR at the same time, which is exactly why both are checked.
- Urinalysis / urine dipstick (urinalysis) can detect larger amounts of protein in urine, along with other things like blood or infection, but it is less sensitive than UACR to the smaller amounts of albumin that appear earliest.
UACR should not be confused with serum creatinine or eGFR — a UACR result on its own does not tell you how well the kidneys are filtering blood, and a creatinine or eGFR result on its own does not tell you whether albumin is leaking into the urine.
When a High UACR Result Needs Confirmation
An initial high UACR is usually repeated, often on a first-morning urine sample, before being treated as confirmed. The National Kidney Foundation and NIDDK both describe repeating the test one or two more times; NICE's guidance describes confirming a moderately elevated ACR with a further early-morning sample, while a very high initial result may not need repeating before further evaluation. Your doctor will decide what's appropriate based on how high the result is and your overall picture.
How Often UACR Should Be Checked
The NIDDK recommends yearly UACR testing for people with diabetes. People with high blood pressure, heart disease, or a family history of kidney disease should ask their own doctor how often they personally need it, since this depends on their individual risk and any previous results. Once albuminuria has been confirmed, monitoring is usually done more often to track whether it is stable, improving, or worsening.
What to Do If UACR Is High
1. Do not panic — expect it to be repeated. One raised reading is usually re-checked once or twice to confirm it before any major decisions are made. 2. Review the likely drivers with your doctor: blood-sugar control, blood pressure, and any recent infection or illness that could have temporarily raised the result. 3. Ask about next steps. Confirmed albuminuria often leads to closer monitoring, blood-pressure and blood-sugar targets, and sometimes medicines chosen by your doctor to help protect the kidneys. A nephrologist may be involved if it persists or worsens.
When to see a doctor
See a doctor promptly if a high UACR comes with swelling of the legs or around the eyes, foamy urine, a marked drop in urine output, or very high blood pressure.
When to Contact a Doctor
Contact your doctor if you receive a UACR result in the A2 or A3 range and have not yet discussed it, if a confirmed high UACR comes with any of the warning signs above, or if you have diabetes or high blood pressure and have not had UACR testing in the past year. This guide cannot replace that conversation — a result is always interpreted alongside your other kidney tests, your overall health, and your personal risk factors.
Disclaimer
This guide is for general education only and does not diagnose or recommend treatment for any individual. UACR results should be interpreted by a doctor alongside your other kidney function tests and risk factors.
Sources
Frequently Asked Questions
What is a normal UACR result?
A normal UACR is below 30 mg/g (below 3 mg/mmol), according to the NIDDK and the National Kidney Foundation. There is no separate normal range published for different age groups.
What does UACR mean?
UACR stands for urine albumin-to-creatinine ratio. It compares the amount of albumin (a protein) to creatinine in a single urine sample, to estimate how much albumin is leaking from the kidneys into the urine.
What does a high UACR mean?
A UACR above 30 mg/g suggests the kidneys are letting more albumin through than normal, which can be an early sign of kidney damage, especially with diabetes or high blood pressure. It does not by itself mean permanent damage — a high result is usually repeated to confirm it before further decisions are made.
What are the A1, A2, and A3 UACR categories?
A1 (below 30 mg/g) is normal to mildly increased. A2 (30–299 mg/g), sometimes called microalbuminuria, is moderately increased and can be an early sign of kidney damage. A3 (300 mg/g or above), sometimes called macroalbuminuria, is severely increased and needs medical follow-up.
Does the UACR test require fasting?
No. UACR does not require fasting. It's best to avoid intense exercise in the 24 hours beforehand, and to tell your doctor about any fever, infection, or menstruation, since these can temporarily raise the result.
Do I need to collect 24-hour urine for UACR?
No. UACR uses a single spot urine sample, often the first-morning sample, rather than a full 24-hour collection. Comparing albumin to creatinine in that one sample corrects for how concentrated or dilute it is.
How often should people with diabetes have a UACR test?
The NIDDK recommends UACR testing at least once a year for people with diabetes, with more frequent monitoring once any kidney damage is identified.
Does a high UACR mean I have chronic kidney disease?
Not by itself. A single high UACR is usually confirmed with repeat testing, and chronic kidney disease is defined by abnormalities that persist for three months or more. One elevated result is a reason to retest and look at the wider picture, not an automatic diagnosis.
What can cause a temporarily high UACR besides kidney disease?
Fever or active infection, a urinary tract infection, intense exercise shortly before the test, menstrual or other urinary bleeding, and poorly controlled blood sugar or a recent blood pressure spike can all temporarily raise a UACR reading.
What is the difference between UACR and eGFR?
UACR looks for albumin leaking into the urine, a sign of damage to the kidneys' filtering units. eGFR estimates, from a blood test, how well the kidneys filter overall. A person can have a normal eGFR and an abnormal UACR at the same time, which is why both are often checked together.
What should I do if my UACR result is high?
Expect the result to be repeated to confirm it, and discuss with your doctor any factors that could have raised it temporarily, such as an infection or poor blood-sugar control. If confirmed, your doctor may recommend closer monitoring, blood-pressure and blood-sugar targets, and sometimes medicines to help protect the kidneys.
Who should have UACR testing?
UACR testing is especially recommended for people with diabetes or high blood pressure, since both are leading causes of kidney damage that can develop silently. People with heart disease or a family history of kidney disease should ask their doctor whether and how often they need it.
Written by JordanMedHub Medical Editorial Team
Updated
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